给RCP中加入jar包与一般的java工程是有些个区别的，否则会出现“java.lang.NoClassDefFoundError”
Open plug-in.xml
Go to Runtime tab.
Click on 'Add...' button in the Classpath section
Add your external jar
As a result my MANIFEST.MF now has the entry
Bundle-ClassPath: lib/myjar.jar,
while my .classpath has the entry
classpathentry kind="lib" path="lib/myjar.jar"